You’ve installed a new roof or simply want to increase the energy savings from solar panels throughout your home. Solar panels are an increasingly popular, excellent way to do so, and for good reason.

They’ve been around for anywhere from 25 to 30 years. In that time, solar panels, which convert sunlight to electricity, have become more widely available from more manufacturers, can be purchased for less money, and have improved wattage. And they’re expected to keep improving and going down in cost as more states follow California’s example and mandate that all new construction be net zero by 2020. Net zero means that a house needs to be constructed so that it produces on site all the energy a typical family living there needs to consume. Solar panels are a big factor in getting to net zero.

Suvi Sharma, CEO of Solaria Corp., Fremont, California.

We talked with two experts about what you need to know to make an intelligent decision in going solar: Suvi Sharma, CEO of Solaria Corp. in Fremont, Calif., a provider of solar module technologies, including the PowerXT 330Wp, and Christina Mathieson, CEO of Clean Energy Options LLC, a program established to educate real estate professionals about energy, based in West Sayville, N.Y.

There are 12 major manufacturers that sell panels in the U.S. Most are based abroad in China, Vietnam, Taiwan and Malaysia. Solaria produces its product both in South Korea and California. A very important decision when deciding on a manufacturer is to purchase rather than lease its panels—the more common route originally, but no longer as costs have come down tremendously. Owning panels can also help to market a house for resale as solar becomes required and desired, says Mathieson.

Efficiency. Panels come with different wattages, and through the years the amount of wattage per panel has increased. It now hovers between 280 and 290. Solaria’s panels provide 330 watts each, says Sharma. Be sure the results promised by any manufacturer have been verified by a third-party laboratory.

Size. Here, too they differ but on average they run from about 3 feet wide to 5 feet long.

Number needed. An entire rooftop doesn’t need to be covered with panels. Instead, the home’s orientation and location will dictate the right number, which a skilled installer will recommend. Most often, they are mounted on south and west facing roofs; north is not ideal since it won’t collect as much sun that it can turn into energy. A wide open area also will permit more sun to shine down and be collected versus a heavily tree-canopied area that won’t permit much sun to come through. An expert software modeling program will guide such choices.

New developments. Most systems rely on a central inverter box but more in the future will integrate microinverters directly within the panels, says Sharma. Future designs may also replace a standard roof structure with just the solar panels, says Mathieson.

Aesthetics. Almost all are black, which is considered the most efficient color, and these are designed as panels but Tesla’s Elon Musk’s coming introduction is said to resemble smaller shingles.

Warranty. Most generally come with a 25-year warranty but even those installed years ago still work—just with less electricity, what’s known in the industry as degradation.

Price. The average system for a “typical-sized” house costs $16,000, which can be greatly reduced by Federal tax credits of 30 percent, which are still available and not expected to be eliminated until the year 2022, says Sharma. Many states, cities, communities, and utility companies help reduce costs further with incentives and rebates so be sure to check in advance for guidelines needed before purchase. One good source is www.dsireusa.org, which lists every state’s incentives.

Images provided by Solaria Corp.

Installation. These days solar panels can go over most types of roof materials such as shingles or slate tiles, but they should be installed over only one roof layer, 4 inches to 5 inches away from the roof to permit air to flow underneath, and on a roof with a 30- to 33-degree pitch, says Mathieson. Whom you hire to do the work is critical in determining how well they operate, says Sharma, who recommends an experienced electrical contractor who has great experience in panels. Key is to know that there is no such thing as a free solar system if a company or installer promises such, says Mathieson. The important questions to ask are:

How many systems have you installed in recent years?

Have you installed similar panels on similar roofs—the same type of roof pitch and with the same type of existing roof materials?

What type of components do you recommend with these—the inverters and mounting systems that hold them in place?

Do you belong to a national organization and/or have certification from a group associated with electrical professionals?

The more research you do in advance, the better. Also go look at houses with solar panels installed so you understand how they will look. And know if you go to sell your home down the road, it should be appraised by a green appraiser who understands the value of the panels in making the house more desirable because of its lower energy costs.